ATM services generally have four different bit rate choices:
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Available Bit Rate: Provides a guaranteed minimum capacity but data can be bursted to higher capacities when network traffic is minimal.
- Constant Bit Rate: Specifies a fixed bit rate so that data is sent in a steady stream. This is analogous to a leased line.
- Unspecified Bit Rate: Doesn’t guarantee any throughput level and is used for applications such as file transfers that can tolerate delays.
- Variable Bit Rate (VBR): Provides a specified throughput, but data is not sent evenly. This makes it a popular choice for voice and videoconferencing